Limestone into compressible artificial stone



UNITED STATES PATENT orrrcn.

CARL LUDWIG VALENTIN ZIMMER, OF BEBLIN-WILMEIBSDOBF, GERMANY, ASSIGNOB,BY MESNE ASSIGNMENTS, TO THE CHEMICAL FOUNDATION, INC., A CORPORATION OFDELAWARE.

PROCESS FOR CONVENTING- LIMESTONE INTO COMPRESSIBLE ARTIFICIAL STONE.

No Drawing.

To all 'whom it may concern:

.Be it known that I, CARL LUDWIG Vanni:- TIN ZIMMER, doctor ofphilosophy, 9. subJect of the King of Prussia, and a resident ofBerlin-\Vilmersdorf, No. 30/31 Pariserstrasse, Germany, have inventednew and useful Improvements in Processes for Convertin Limestone intoCompressible Artificial tone, of which the following is a specification.

Heretofore no process was known for producing an artificial stone whichhas the property of decomposing to a powder when heated, and ofregaining its original hardness under pressure.

Only natural asphaltic limestone, as found at but a few places on theearth in limited quantities, has the specially characteristic propertythat, when heated to 1'50200 (3., it decomposes to a brown, loose powderwhich can be compressed by pressure to the hardness of the originalstone. Owing to these properties compressed asphalt, made from asphalticlimestone, is so extensively used for roa s, and the like, which satisfyall requirements in regard to resistance to mechanical stresses of allkinds, to frost and heat, etc.

Not every asphaltic limestone can be used directly for making roads, butonly such sorts as contain 85-12% bitumen, whose melting point, however,is not higher than 50 C, (regulation of the road authorities). If bothrequirements are not satisfied, the compressed asphalt will not meet alldemands of practice in re ard to durability, softening point, etc. s,now, even in one and the same mine, the amount of bitumen contained inthe stone varies very much, it is extremely diflicult to obtain a reallygood material. i The reason for the great advantages of com ressedasphalt made from the natural pro not was considered to be due to theintimate mechanical mixture of the two components: limestone andbitumen. Various attempts have therefore been made to add bitumen toasphaltic limestone containing too little bitumen. Heat was also used toassist the operation, or bitumen was emloyed in the form of an emulsion.It is l iowever not possible to obtain a ood comhalt by such means. hemass pressed as r as only the properties of cast obtained Specification0! Letters Patent.

by Dr. H. Koh

Patented Oct. 28, 1919.

Application iilefl August 11, 1915. Serial No. 45,028.

asphalt, because according to the processes mentioned the bitumen wasonly brought nto mechanical contact with the stone, or, m other words,only surrounds same. Furt-her, all experiments made to mix powderedlimestone or chalk with bitumen or other additions (compare ChemicalTechnology er, page 146) have not resulted in producing a compressibleasphalt, but only a product having the properties of cast asphalt, thatis, it melts when heated, and it cannot 'be compressed, when itsolidifies. This non-success was, in the first place, due to the factthat th chemical process, which unmistakably takes place between thebltumen and limestone in nature, was not recognized. Consequently, anexpert came naturally to the conclusion that the artificial productionof a stone, which, on being heated, decompose to a loose powder, and canthen be compressed, is quite impossible.

Now, according to the present invention, it is rendered possible toproduce a compressible asphalt synthetically, which not only in analysisand use shows the properties of natural asphaltic limestone, but evenexceeds same by the fact that not only quantity of bitumen, but also thesoftening point of the bitumen can be chosen within the widest limits,and thus the most advantageous composition for any given purpose can beobtained.

In the endeavor to investigate, and, if ible, to imitate, the o erationswhich take place in the natural ormation of asphaltic limestone, theinventor first ascertained that the formation of the natural productcannot have taken place in hot condition, because natural asphalticlimestone contains very low boiling hydrocarbons, which are essentiallynecessary to obtain the desired roperties, and could not be present, ifa big er temperature came into question. Further, it was recognized thatthe formation could not have taken place by bitumen being simply mixedwith finely powdered limestone, but that rather a chemical rooess musthave taken lace. Considerations of this and other kin s, convinced theinventor that the process in nature must have, been of a chemicalcharacter.

Many experiments were made with the object of repeatin this processartificially, till finally the uni orm presence of sulfur in naturalasphaltic limestone led to the out 1 T e material used for the purposeconsists, 'on the one hand, as in the case of the natural product, oflimestone, or any stone containing lime, such as calcareous spar,marble, chalk, etc.

The second material used, as in nature, is some bituminous substance,such as natural asphalt, vegetable and animal oils, mineral. oils,mineral oil residues, tar, tar oil residues and distillates.

If such bituminous substances, by means of sulfonated sebacic acid, oralkaline salts thereof, are converted into an emulsion, this emulsion,in a very dilute condition, will have the pro erty, even at ordinarytemperature, to quic 1y react on thewdered limestone, and will form anartificial asphaltlc limestone having all the properties set forthabove, the attainment of which forms the object of the presentapplication.

The chemical reaction, which takes place between the sebacic acid andthe powdered limestone, causes an intimate union of the limestone andbituminous substances to, be effected.

For the purpose in question sulfo-acids of animal and vegetable oil andfats, or their salts, are very suitable. Sulfonated ricinoleic acidshave been found to be of particular advantage. When such are used thereaction is finished in a few minutes, and after mixing the materialsthe vessel must be quickl emptied, so quickly does the reaction ta eplace. The product obtained is at first an extremely lastic kneadablemass which decisively repe water.

pres- The present process is, of course, an invention of the greatestimportance. It is not only suitable to entirely replace natural asphalt,but is even supenor to such, inasmuch as this artificial as halticlimestone, as above mentioned, aifor I the possibility of choosing ineach case a composltion suitable for the particular conditions andtemperature.

What I claim and desire to secure by Letters Patentof the United Statesis 1. The herein described process of converting limestone intocompressible artificial stone which consists in mixing limestone in thepresence of a bituminous substance, with a sulfated ricinoleic acidcapable of emulsifyinlg such bituminous substance.

2. he herein described process of converting limestone into compressibleartificial stone which. consists in mixing powdered limestone with abituminous substance in the presence of a sulfated non-mineral acidcapable of emulsifying the bituminous substance.

3. The herein described process of converting limestone intocompressible artificial stone which consists in mlxinglpowderedlimestone with a bituminous substance in the presence of a sulfatedvegetable acid capa le of emulsifying the bituminous substance.

In testimony whereof, I have signed my nam to this specification in thepresence of two subscribing witnesses.

CARL LUDWIG VALENTIN ZIMMER.

Witnesses:

WOLDEMAR HAUPT, HENRY Hasrna.

